The invention relates to a method suitable to produce a nonwoven fabric with a uniform thickness. Further the invention relates to apparatus suitable to carry out the method.
Nonwoven fabrics produced employing various staple fibers such as for example polypropylene, nylon, polyvinylchloride, cotton, wool, etc. are well known in the art. Various methods are known to produce such nonwoven fabrics from staple fibers. One method commonly employed involves forming a nonwoven fabric by crosslapping carded webs of staple fibers using crosslappers, passing the nonwoven fabric formed from the crosslapped carded webs to one or more needle looms to needle punch the nonwoven fabric which forces filaments in the various webs into one another thus bonding the webs together to provide integrity to the fabric. Such nonwoven fabrics when fused on one or both sides are useful for such products as carpet backing, upholstery stretching strips, mattress ticking, etc.
A relatively new use for such nonwoven fabrics which are generally unfused is for backing polymeric films to produce unholstery material as is known in the art. Although the use of such upholstery material has been accepted in the industry with considerable success, there is a problem in cutting the material into patterns. This problem involves the lack of uniformity in thickness of such crosslapped nonwoven fabrics because the crosslapping of the webs causes the edge portions of such fabrics to be thicker than the middle portion of the fabric. The nonwoven fabric is generally produced by the manufacturer in widths of approximately 15 feet. Since the upholstery industry generally manufactures upholstery goods in widths substantially less than 15 feet, such as approximately 4 feet, 6 inches, the nonwoven fabric with a width of 15 feet is cut into three 5 foot widths by the nonwoven fabric manufacturer, and then trimmed to 4 feet, 6 inches by the upholstery goods manufacturer. Thus, two of the three 5 foot widths of fabric have one edge thicker than the other. The 5 foot width nonwoven fabric is then coated with a polymeric material generally employing the direct calender lamination or the post lamination technique known in the art to produce the nonwoven backed upholstery material. As noted above it is common for the upholstery industry to cut such upholstery material into patterns. It is also common to cut a number of pieces of the material at the same time by cutting stacks of the material, that is, cutting several pieces of the material which are stacked one above the other. A problem arises when cutting stacks of the material because the two 4 foot, 6 inch width pieces made from the 5 foot width outside edge pieces of the 15 foot width material do not have a uniform thickness. When the nonwoven backed upholstery material is stacked for cutting the nonuniformity of the nonwoven backing material is magnified which results in poor pattern definition. The present invention provides a method and apparatus useful for producing a nonwoven fabric with a uniform thickness which results in the elimination of the above-described cutting problems when such fabric is used as the backing in the upholstery material.
An object of the invention is to produce a nonwoven fabric with a uniform thickness.
Another object of the invention is to reduce the thickness of the edges of a nonwoven fabric formed by crosslapping webs.
Another object of the invention is to provide apparatus suitable for the production of a nonwoven fabric having a uniform thickness.
Other objects, advantages, and aspects of the invention will be apparent to those skilled in the art after studying the specification and the appended claims.
According to the present invention a nonwoven fabric having thickened edge portions is passed through a compression zone wherein the edge portions of the fabric are compressed to produce a nonwoven fabric with a uniform thickness. It is generally desirable to pass the fabric to the compression zone as the fabric is being produced.
Further according to the invention apparatus comprises a first roll with a fixed axis; a second roll with a movable axis, the axis of the second roll positioned adjacent and approximately parallel to the first roll to form a nip with the first roll; two bearings each mounted on a slidable support one for supporting one end and one for supporting the other end of the axis of the second roll; and two means, one attached to one of the supports and one attached to the other, the means for positioning each end of the axis of the second roll in a direction normal to the axis of the first roll.